Abstract:Prior study of Middle Holocene (~7,500- 3,700 years cal BP) Cis-Baikal hunter-gatherers has documented considerable chronological and geographic variation in the lifeways of these past people. However, how child health and behavior varied across time and space in these populations remains insufficiently understood. To provide new insight into these questions, skeletal growth was explored from a biomechanical perspective. Comparisons of growth in bone strength and shape in Middle Holocene Cis-Baikal individuals from different archaeological periods and cemeteries indicate a decrease in developmental stress, mobility, and how hard children worked from the Early Neolithic to the Late Neolithic. Also, the comparisons suggest geographic heterogeneity in child health and behavior during the Middle Holocene. Chronological and regional variation in child behavior and health may reflect differences in resource distribution and abundance, population density, and the extent to which children were involved in subsistence activities. By the end of adolescence, females and males exhibit differences in bone strength and shape consistent with an emerging sexual division of labor. Overall, these findings advance the study of Middle Holocene Cis-Baikal lifeways, providing a better understanding of what childhood was like in these populations. More broadly, the findings demonstrate that biomechanical analysis can provide new insights on the biology and behavior of children in the past.